I'd go with a disk problem, and ignore the NOLOCK part of the error message. That specific error can be thrown if there is a corrupt page encountered while running a query. Are there any 823 or 824 errors in the SQL error log? Is page 9:3:210666 OK?

DBCC TRACEON(3604);

DBCC PAGE(9,3,210666,1);

That should return with no errors. If there are errors, they may not be detected unless you have Torn Page Detection or Checksum set as the page-verify option for the database (checksum is highly preferred).

The corruption may exist on a different page, or it may be a case of the RAID controller intermittently failing.